Among the barrage of countermeasures Beijing unveiled in response to the latest round of US sanctions, one in particular stands out: a national security investigation into imported printers and photocopiers that use foreign-developed software.The move raises two questions: why does this matter, and how has seemingly mundane office equipment become a national security concern? Here’s what you need to know.What is the investigation?The investigation was launched under Article 41 of China’s Foreign Trade Law, which allows the Ministry of Commerce to investigate foreign trade matters involving national security interests, according to a statement by the ministry on Wednesday.The ministry will examine the import scale, the effect of the products, technologies and services on national security, China’s domestic demand and industrial capabilities, as well as the effects of foreign government policies and measures.Why is this round different?The commerce ministry said the move marked China’s first national security investigation into foreign trade.“The biggest difference is that this probe is rooted in national security risks,” said Wu Xinbo, dean of the Institute of International Studies at Fudan University in Shanghai.